The hypothesis for this study is that the prolongation of the partial thromboplastin time (PTT) is caused by a lupus anticoagulant, which is likely produced in response to viral infections. The study will attempt to identify the cause of prolongation of the PTT in children with fever and petechiae, and may help the scientific community better understand the interaction between viral and bacterial infections and the human clotting system. Background: Children with fever and petechiae are known to be at increased risk for serious bacterial infections, including bacteremia, sepsis, and meningitis. Previous studies have attempted to identify the incidence of and risk factors for serious bacterial illnes in these children. A recent study found that only 2% of children with fever and petechiae had bacteremia or sepsis. They noted that prothrombin time (PT) or PTT was prolonged in 28% of children with fever and petechiae. Though these children were not noted to have bleeding problems related to their prolonged coagulation times, this finding suggested that the source of the fever and petechiae in these children interacts with the human clotting system in a fashion that the investigators have yet to identify. The study will include 3 distinct patient populations: 1) children with fever and petechiae without bacteremia or sepsis; 2) children with fever without petechiae; and 3) children with neither fever nor petechiae.